The invention is based on an apparatus for adjusting a rotational angular relationship of a camshaft, as defined hereinafter. In an apparatus of this kind known from European Patent Document A 0 163 046, two hydraulic control motors, disposed on a diameter of a part connected to the camshaft and each having an adjusting piston that acts via a roller on a ramp, are provided, the rollers are disposed on a drive gear radially surrounding the part connected to the camshaft. The ramps associated with each control motor are inclined oppositely, so that upon an adjustment of the adjusting piston of one control motor, the camshaft is adjusted relative to the drive gear via the ramps such that the opposite ramp forces the adjusting piston of the other control motor backward. The control motors are triggered by valves or a slide valve such that pressure is exerted upon the piston of one control motor, which has been moved outward, while the work chamber of the other control motor opposite it is relieved, enabling the piston of that control motor to deflect along the ramp. This apparatus is relatively expensive because a separate pressure source must be furnished, along with two magnetic valves or one three-position valve for triggering the control motors. Although an existing oil pressure source in an internal combustion engine could be used as the pressure source, it runs at relatively low pressure. If this pressure source is needed to adjust the camshaft as well, then the pressure pump for bringing this pressure to bear must be larger than usual, because given the manner of triggering of the hydraulic control motors, a relatively large quantity of pressure oil is used. At the relatively low pressure, either the known apparatus operates only quite slowly or else very large control motors must be installed, which in turn use up a large quantity of pressure fluid and occupy a disadvantageously large amount of space. A separate high-pressure pump, on the other hand, is very expensive and consumes a large amount of energy.